Trypanosoma cruzi is the protozoan parasite that causes American trypanosomiasis, or Chagas disease. This illness is a major cause of morbidity and death in Latin America, and tens of thousands of T. Cruzi- infected immigrants from countries in which Chagas disease is endemic now reside in the United States. Identification of infected persons is important so that appropriate monitoring and treatment can be undertaken, and also to prevent transmission by transfusion of contaminated blood. Conventional serologic assays, which are based on native antigens, are generally sensitive but often lack specificity, resulting in misdiagnoses in clinical settings and the needless discarding of donated units in blood banks due to false positive test results. The goal of the proposed project is to develop an improved assay for detecting T. cruzi infection through the application of recombinant DNA technology. The general approach to be used will involve inserting cloned T. cruzi genes that encode antigenic proteins into a plasmid vector and producing recombinant proteins in Escherichia coli. The engineered hybrid antigens will contain one, two or three distinct T. cruzi proteins. After purification of the proteins, the sensitivity and specificity of ELISAs in which they are used as target antigens will be assessed by testing geographically and medically diverse groups of well-characterized sera from persons with and without T. cruzi infection. This work will extend preliminary studies in which it was demonstrated that recombinant T. cruzi proteins can serve as target antigens in sensitive and specific ELISAs. This innovative application of recombinant DNA technology to developing assays for detecting T. cruzi infection will provide the basis for more accurate clinical testing and more effective blood bank screening programs in endemic Latin America countries and also in the United States. PROPOSED COMMERCIAL APPLICATION Serologic testing for T. cruzi infection is widespread in Latin America in clinical settings as well as in blood banks. The assay that may result from the proposed research would meet the need for an improved diagnostic test in the large Latin American market. In addition, since large numbers of immigrants from Central and South America now reside in the U.S., the market here for an improved assay is growing and will expand enormously if serologic screening for T. cruzi in our blood banks is undertaken.